The present invention relates to optical assemblies which direct light from two light sources of different spectral characteristics into two different beam patterns, and particularly to the use of such optical assemblies as automobile headlights. Related inventions are described in my prior U.S. Pat. No. 4,536,833 and in my copending applications Ser. Nos. 897,294, 897,295, and 897,292.
There are currently two different methods of generating multiple light beams or patterns of light distribution. One method uses multiple light sources and a common set of optics while the other uses a fixed light source and multiple optical elements. Each of the techniques has specific trade-offs associated with it.
The first technique is commonly applied to generating the high and low beams of an auto headlight. To accomplish this, two spatially fixed light sources and reflectors are used with a single lens element. The lens is designed to generate two different light distribution patterns, corresponding to the high and low beams, depending on which of the light sources is energized. The lens design, optimized to work for both desired beams, sacrifices overall efficiency to heat loss and glare.
The second technique, presently employed in optical scanners and bar code readers, utilizes a fixed light source and multiple optical elements moved in the path of the light source by a motor. Each optical element is designed to change the path of the light at one specific angle and is extremely precise. These systems tend to be complex and therefore, expensive; and, because they are motorized, the overall reliability of the system is reduced.